Coagulation of dust aggregates plays an important role in the formation of planets and is of key importance to the evolution of protoplanetary disks (PPDs). Characteristics of dust, such as the diversity of particle size, porosity, charge, and the manner in which dust couples to turbulent gas, affect the collision outcome and the rate of dust growth. Here we present a numerical model of the evolution of the dust population within a PPD which incorporates all of these effects. The probability that any two particles collide depends on the particle charge, cross-sectional area and their relative velocity. The actual collision outcome is determined by a detailed collision model which takes into account the aggregate morphology, trajectory, orientation, and electrostatic forces acting between charged grains. The data obtained in this research reveal the characteristics of dust populations in different environments at the end of the hit-and-stick growth, which establishes the foundation for the onset of the next growth stage where bouncing, mass transfer and fragmentation become important. For a given level of turbulence, neutral and weakly charged particles collide more frequently and grow faster than highly charged particles. However, highly charged particles grow to a larger size before reaching the bouncing barrier, and exhibit a "Runaway" growth, in which a few large particles grow quickly by accreting smaller particles while the rest of the population grows very slowly. In general, highly charged aggregates have a more compact structure and are comprised of larger monomers than neutral/weakly charged aggregates. The differences in the particle structure/composition not only affect the threshold velocities for bouncing and fragmentation, but also change the scattering and absorption opacity of dust, influencing the appearance of PPDs.
Formation of aqua planets with water of nebular origin: Effects of water enrichment on the structure and mass of captured atmospheres of terrestrial planets
Spatial distribution of water ice in the protoplanetary silhouette disk d216-0939
Kiel University（基尔大学）；Friedrich Schiller University Jena（耶拿弗里德里希·席勒大学）；Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）；National Astronomical Observatory of Japan（日本国立天文台）
Episodic planetesimal disruptions triggered by dissipation of gas disk
Nanjing University（南京大学）；Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University（教育部现代天文与天体物理重点实验室，南京大学）；State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits & Lunar and Planetary Science Institute, School of Earth Sciences and Engineering, Nanjing University（南京大学地球科学与工程学院关键地球物质循环与矿床国家重点实验室及月球与行星科学研究所）；CAS Center for Excellence in Comparative Planetology（中国科学院比较行星学卓越创新中心）
